Flexible LED strips have been used for the purpose of illumination and decoration. For example, LED strips are attached to the surface of a frame which takes various shapes such as Santa Claus. However, there are two problems associated with such a design. First, the attachment of the LED strip to the frame surface is difficult to be automated, and therefore the manufacture process is complex, labor intensive and time-consuming. Second, the lighting effect and visual appearance of the design is unsatisfactory. For example, when the LED strip lights up, what a viewer can observe is a cluster of glaring “LED spots” or “bright spots” and a dimmed image of Santa Claus. The viewer cannot see a vivid Santa Claus that is per se “glowing” solidly and brightly. Therefore, there exists a need in the field to design a lighting article such as Santa Claus with improved optical properties, including more homogenous distribution of photons within the frame, enhanced brightness of the “glowing” Santa Claus per se, and less perception of glaring LED spots. There also exists a need in the field to design a manufacturing process that is simple, automatable, and highly efficient.
Peeters et al have disclosed a LED strip for the illumination of channel signs in US Published Patent Application 2012/0000104. To mount a flexible LED strip in a channel sign, a clip needs to be attached to an interior surface of the channel sign. Then an end of the LED strip is manually folded back and the LED strip including the folded end is manually fixated using the clip. However, such a process is defective in that it is complex, labor intensive, and time-consuming, and therefore cannot be automated.
U.S. Pat. No. 6,478,450 to Grajcar discloses a lighting system for channel signs comprising a flexible conductor strip that can be mounted to a structure of a channel sign and to which light sources, e.g., LEDs, can be electrically connected. The disadvantages of such a lighting system are that (1) it is difficult to make it waterproof, and (2) a viewer still suffers the observation of glaring “bright spots”.
U.S. Pat. No. 4,271,458 to George discloses a decorative light tube. The tube houses unbased miniature lamps. The lamps are connected in series by soldering or welding the ends of the flexible wire leads together to form parallel strings between a pair of elongated parallel wire conductors. The tube is substantially filled with mineral oil or other clear, viscous dielectric fluid to protect the lamps and wiring against the adverse effects of vibration, shock and moisture. The disadvantages of George's tube are that (1) mineral oil or other clear, viscous dielectric fluid can have leakage problem, and cannot give the lamps a robust protection; and (2) a viewer still suffers the observation of glaring “bright spots”.
Advantageously, the present invention can solve at least one of the above problems by employing an elongated structure having a groove along the elongation direction, into which a solid matrix embedding a LED strip is fitted.